Apollo Federation concepts in GraphQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a federated service with a key directive.

GraphQL

type Product @key(fields: "[1]") {
  id: ID!
  name: String
}

Drag options to blanks, or click blank then click option'

Aname

Bid

Csku

Dprice

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-unique field like 'name' as the key.

Omitting the @key directive entirely.

The @key directive specifies the primary field used to uniquely identify the entity across services. Here, id is the correct key field.

2fill in blank

medium

Complete the code to extend a type from another federated service.

GraphQL

extend type User @key(fields: "[1]") {
  id: ID! @external
  reviews: [Review]
}

Drag options to blanks, or click blank then click option'

Aid

Bprofile

Cusername

Demail

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-key field in the @key directive.

Not marking the key field as @external.

The extend keyword is used to add fields to a type defined in another service. The @key directive must reference the unique identifier field, which is usually id.

3fill in blank

hard

Fix the error in the code by completing the directive to specify the field used for reference resolution.

GraphQL

type Review @key(fields: "[1]") {
  id: ID!
  body: String
  author: User @provides(fields: "username")
}

Drag options to blanks, or click blank then click option'

AauthorId

Breviewer

CuserId

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-existent or incorrect field name in @key.

Confusing @provides with @key directive usage.

The @key directive must reference the unique identifier field of the type, which is id in this case.

4fill in blank

hard

Fill both blanks to correctly define a federated entity with a reference resolver.

GraphQL

extend type Product @key(fields: "[1]") {
  id: ID! @external
  price: Int
  weight: Int
}

const resolvers = {
  Product: {
    __resolveReference(product) {
      return [2];
    }
  }
};

Drag options to blanks, or click blank then click option'

Aid

Bproduct.id

Cproduct

Dprice

Attempts:

3 left

💡 Hint

Common Mistakes

Returning only a field like product.id instead of the full product.

Using a wrong field name in the @key directive.

The @key directive must specify the unique identifier field id. The __resolveReference function receives the reference object and returns the full entity, so returning product is correct.

5fill in blank

hard

Fill all three blanks to define a federated schema with a service and a query that fetches an entity by key.

GraphQL

type Query {
  productById(id: ID!): Product
}

type Product @key(fields: "[1]") {
  id: ID!
  name: String
  price: Int
}

const resolvers = {
  Query: {
    productById(_, args) {
      return [2];
    }
  },
  Product: {
    __resolveReference(reference) {
      return [3];
    }
  }
};

Drag options to blanks, or click blank then click option'

Aid

Bproducts.find(p => p.id === args.id)

Cproducts.find(p => p.id === reference.id)

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong field names in the @key directive or resolvers.

Returning incomplete objects in __resolveReference.

The @key directive uses id as the unique identifier. The productById query resolver finds the product by matching args.id. The __resolveReference resolver finds the product by matching reference.id.